The UK's longest heatwave events and where they happened

As the UK continues to experience more frequent and intense heatwaves, it’s worth reflecting on some of the most prolonged periods of high temperatures recorded across the country. 

In the UK, a heatwave is officially defined when a location records at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold. This threshold varies by county, reflecting the diverse climate across the UK.  

Originally, these thresholds were based on the 1981-2010 climatology of daily maximum temperatures at the mid-point of the meteorological summer (15 July), but were updated ahead of Summer 2022 to use the most recent 1991-2020 climate averaging period as the UK began to see impacts due to climate change. 

Using historical Met Office data, we’re looking back at some of the notable heatwave spells across the UK. 

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The UK’s most enduring heatwaves 

The summer of 1976 remains one of the most iconic in UK weather history. During this period, multiple locations across England recorded heatwave spells lasting over two weeks. At the top of the list is Cheltenham, in Gloucestershire, which experienced temperatures exceeding 32°C for 7 days.  

Cardington in Bedfordshire and Heathrow in Greater London are also worth mentioning as both experienced 16 consecutive days of temperatures exceeding 30°C from 23 June to 8 July 1976. 

Other locations such as Benson (Oxfordshire) and Aylesbury (Buckinghamshire) also recorded heatwaves lasting 14-15 days during the same period. These extended spells of heat were widespread across southern and central England, with many sites reporting 13 or more consecutive days above 30°C. 

England: The epicentre of prolonged heat 

England has historically borne the brunt of the UK’s most intense and long-lasting heatwaves. The 1976 event dominates the records, but more recent heatwaves have also made their mark. In August 2003, Wisley (Surrey) recorded 10 days of temperatures above 30°C. 

The 2022 heatwave also stands out, with multiple locations in southeast England exceeding 30°C for several consecutive days. These events highlight the increasing frequency of extreme heat in recent decades. 

Scotland: Shorter but still significant 

While Scotland typically experiences shorter and less intense heatwaves compared to southern parts of the UK, it has still seen notable events. Heatwaves in Scotland are defined as periods of three-days or more above 25°C. 

The longest recorded heatwave in Scotland occurred at Glentress in Peeblesshire, where temperatures exceeded 28°C for 8 consecutive days in July 1976, demonstrating that even northern regions are not immune to prolonged periods of heat. More recently, Glentress also recorded a 5-day heatwave in August 2003, with temperatures above 25°C. 

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Wales: Recurrent spells of summer heat 

Wales has experienced several notable heatwaves, particularly in the south. Like heatwave criteria in Scotland, heatwaves in Wales are also defined as periods of three-days or more above 25°C. 

In July 1976, locations such as Gogerddan (Dyfed) and Cilfynydd (Mid Glamorgan) recorded 6–7 days of temperatures above 30°C. More recently, Cardiff Bute Park and St Athan experienced 5-day heatwaves in August 2022, with temperatures consistently exceeding 30°C. 

These events show that while Wales may not see the same duration of heat as parts of England, it is still susceptible to significant summer heat events. 

Northern Ireland: Rare but notable heatwaves 

Northern Ireland’s climate typically limits the duration and intensity of heatwaves, but there have been exceptions. As with Scotland and Wales, heatwaves in Northern Ireland are also defined as periods of three-days or more above 25°C. 

In July 2021, Thomastown (Fermanagh) recorded a 5-day heatwave, with temperatures exceeding 28°C. Similar events were recorded at Knockarevan and Strabane in 1976. 

Although less frequent, these events are important reminders of the variability and reach of high temperatures across the UK. 

Regional comparisons and trends 

Across all regions, the summer of 1976 remains the benchmark for prolonged heat in the UK. England, in particular, experienced widespread and extended heatwaves, with multiple locations recording 13–16 consecutive days above 30°C. Scotland and Wales also saw significant heat during this period, though for shorter durations. 

In more recent years, heatwaves have become more frequent and widespread. The 2003, 2021, and 2022 events brought high temperatures to regions that historically experienced fewer extreme heat days. This trend aligns with broader climate observations indicating a warming climate and increasing likelihood of extreme weather events. 

Looking ahead 

As the climate continues to change, the UK is likely to see more frequent and intense heatwaves. Understanding past events helps us prepare for future extremes. The Met Office continues to monitor and analyse temperature trends to provide accurate forecasts and timely warnings, helping communities stay safe during periods of extreme heat. 

Keep up to date with weather warnings, and you can find the latest forecast on our website, on YouTube, by following us on X and Facebook, as well as on our mobile app which is available for iPhone from the App store and for Android from the Google Play store.